1. Field of the Invention
The present invention relates to a pipe joint structure and a method for fabricating the same in which a pipe is provided with an annular protrusion protruding radially outward, and this annular protrusion and a through hole part in a connection flange member are press-fitted and fixed to each other. The invention is suitably applicable to a refrigerant pipe joint of a vehicle air conditioning refrigeration system, for example.
2. Description of the Related Art
FIG. 22 shows a conventional pipe joint structure disclosed in Japanese Patent Laid-Open Publication No. Hei 4-266521. In this conventional art, an annular protrusion 16 protruding radially outward is formed near an end of a pipe 11 by bulging. Two split flange members 10A and 10B split along the axial direction of the pipe 11 are also provided. The two split flange members 10A and 10B are coupled with each other by fitting arcuate recesses 10C and 10D of the two split flange members 10A and 10B to the pipe 11, and sliding either one of the split flange members, 10B, with respect to the other split flange member 10A along the axial direction of the pipe 11 as shown by the arrow J.
Two split flange members 10A, 10B are moved toward the end of the pipe 11 until enlarged recesses 10E, 10F formed in the end side of the two split flange members 10A, 10B, respectively, come into contact with the annular protrusion 16 of the pipe 11. In this state, the two split flange members 10A, 10B are fastened by screws (not-shown) so that the pipe 11 and the two split flange members 10A, 10B are fixed to each other.
In the conventional art described above, the one split flange member 10B needs to be slid with respect to the other split flange member 10A along the axial direction of the pipe 11 as shown by the arrow J, so that the pipe 11 requires a straight part K to facilitate sliding. This results in the problem of an inevitable increase in the height H of the pipe joint. In applications of extremely tight mounting spaces, such as a vehicle, the increased height H can sometimes prevent the adoption of the foregoing conventional art.
Therefore, a pipe joint comprising an aluminum block member has been put to practical use. Here, the block member is cut to have a pipe connecting part having an annular concave groove for accommodating an O-ring, a passage hole communicating with the pipe connecting part, and so on. A pipe end is inserted into the passage hole and brazed, whereby the height H of the pipe joint is reduced. Nevertheless, this conventional art requires laborious cutting, and additionally requires brazing aside from the cutting. There has thus been the problem of a significant increase in fabrication costs.